ATF agents are being sent to retrieve more firearms from people who should have never been able to buy them. Here is an in-depth look into the FBI background-check system and why things go wrong. Illustration: Laura Kammermann

Play Video

ATF agents are being sent to retrieve more firearms from people who should have never been able to buy them. Here is an in-depth look into the FBI background-check system and why things go wrong. Illustration: Laura Kammermann

Michael Alan Chance Green, who worked on a ranch as a cowboy, was obsessed with professional wrestler and entertainer Terry Funk. He believed he had to warn him of imminent danger and delivered bizarre handwritten letters to Mr. Funk’s mailbox, until he was charged with stalking.

A Texas judge hearing the case declared Mr. Green mentally incompetent and committed him to a state hospital.